Saturday, January 9, 2016

Fabric Construction – Leather[1]
Art Resource

Marie-Therese Wisniowski

This is the forty-eight post in the "Art Resource" series, specifically aimed to construct an appropriate knowledge base in order to develop an artistic voice in ArtCloth.

Other posts in this series are:
Glossary of Cultural and Architectural Terms
Units Used in Dyeing and Printing of Fabrics
Occupational, Health & Safety
A Brief History of Color
The Nature of Color
Psychology of Color
Color Schemes
The Naming of Colors
The Munsell Color Classification System
Methuen Color Index and Classification System
The CIE System
Pantone - A Modern Color Classification System
Optical Properties of Fiber Materials
General Properties of Fiber Polymers and Fibers - Part I
General Properties of Fiber Polymers and Fibers - Part II
General Properties of Fiber Polymers and Fibers - Part III
General Properties of Fiber Polymers and Fibers - Part IV
General Properties of Fiber Polymers and Fibers - Part V
Protein Fibers - Wool
Protein Fibers - Speciality Hair Fibers
Protein Fibers - Silk
Protein Fibers - Wool versus Silk
Timelines of Fabrics, Dyes and Other Stuff
Cellulosic Fibers (Natural) - Cotton
Cellulosic Fibers (Natural) - Linen
Other Natural Cellulosic Fibers
General Overview of Man-Made Fibers
Man-Made Cellulosic Fibers - Viscose
Man-Made Cellulosic Fibers - Esters
Man-Made Synthetic Fibers - Nylon
Man-Made Synthetic Fibers - Polyester
Man-Made Synthetic Fibers - Acrylic and Modacrylic
Man-Made Synthetic Fibers - Olefins
Man-Made Synthetic Fibers - Elastomers
Man-Made Synthetic Fibers - Mineral Fibers
Man Made Fibers - Other Textile Fibers
Fiber Blends
From Fiber to Yarn: Overview - Part I
From Fiber to Yarn: Overview - Part II
Melt-Spun Fibers
Characteristics of Filament Yarn
Yarn Classification
Direct Spun Yarns
Textured Filament Yarns
Fabric Construction - Felt
Fabric Construction - Nonwoven fabrics
A Fashion Data Base
Fabric Construction - Leather
Fabric Construction - Films
Glossary of Colors, Dyes, Inks, Pigments and Resins
Fabric Construction – Foams and Poromeric Material
Glossary of Fabrics, Fibers, Finishes, Garments and Yarns
Weaving and the Loom
Similarities and Differences in Woven Fabrics
The Three Basic Weaves - Plain Weave (Part I)
The Three Basic Weaves - Plain Weave (Part II)
The Three Basic Weaves - Twill Weave
The Three Basic Weaves - Satin Weave
Figured Weaves - Leno Weave
Figured Weaves – Piqué Weave
Figured Fabrics
Glossary of Art, Artists, Art Motifs and Art Movements
Crêpe Fabrics
Crêpe Effect Fabrics
Pile Fabrics - General
Woven Pile Fabrics
Chenille Yarn and Tufted Pile Fabrics
Knit-Pile Fabrics
Flocked Pile Fabrics and Other Pile Construction Processes
Glossary of Paper, Photography, Printing, Prints and Publication Terms
Napped Fabrics – Part I
Napped Fabrics – Part II
Double Cloth
Multicomponent Fabrics
Knit-Sew or Stitch Through Fabrics
Finishes - Overview
Finishes - Initial Fabric Cleaning
Mechanical Finishes - Part I
Mechanical Finishes - Part II
Additive Finishes
Chemical Finishes - Bleaching
Glossary of Scientific Terms
Chemical Finishes - Acid Finishes
Finishes: Mercerization
Finishes: Waterproof and Water-Repellent Fabrics
Finishes: Flame-Proofed Fabrics
Finishes to Prevent Attack by Insects and Micro-Organisms
Other Finishes
Shrinkage - Part I
Shrinkage - Part II

There are currently eight data bases on this blogspot, namely, the Glossary of Cultural and Architectural Terms, Timelines of Fabrics, Dyes and Other Stuff, A Fashion Data Base, the Glossary of Colors, Dyes, Inks, Pigments and Resins, the Glossary of Fabrics, Fibers, Finishes, Garments and Yarns, Glossary of Art, Artists, Art Motifs and Art Movements, Glossary of Paper, Photography, Printing, Prints and Publication Terms and the Glossary of Scientific Terms, which has been updated to Version 3.5. All data bases will be updated from time-to-time in the future.

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The Art Resource series will be the first post in each calendar month. Remember - these Art Resource posts span information that will be useful for a home hobbyist to that required by a final year University Fine-Art student and so undoubtedly, some parts of any Art Resource post may appear far too technical for your needs (skip over those mind boggling parts) and in other parts, it may be too simplistic with respect to your level of knowledge (ditto the skip). The trade-off between these two extremes will mean that Art Resource posts will hopefully be useful in parts to most, but unfortunately may not be satisfying to all!

Leather is not a textile in the strictest definition. Nevertheless, it can have a fabric-like hand and drape and so is often talked and written about in a textile context. Leather is a natural product but nevertheless it is included in this Art Resource series because many man-made fabrics are finished to resemble leather in appearance.

Leather is a product manufactured from the skins of animals, reptiles, fish and birds. It is an organic substance derived from living animals and therefore varies significantly in uniformity. The hides and skin varies in size, thickness, uniformity and grain and often are marred by scratches, brands and so on. Animals are generally not raised for their hides, but more for their meat and fiber. Leather is a relatively unimportant by-product. Since the value of the hide is generally only 5% of the value of the animal, an increase in the demand for leather would not lead to an increase in the number of animals raised.

Gucci’s python peplum jacket.

Hides undergo many processes before they become a leather product. Some of these are:
(i) In the packing factory plants, the skin is removed (flayed) and dropped down a chute to a hide cellar in order to allow the skin to cool. Hides are covered with salt on the flesh side to prevent putrefaction. They are piled into packs and allowed to cure for 30 days at 50-60oF. These are green salted hides.

Salted Cattle hides.

In the past few years pig skin has become a fairly plentiful raw material for leather because of the popularity of packaged bacon rather than slab bacon. Some leather firms supply flaying machines to packing plant in order to ensure a plentiful supply of well-flayed hides.

The luxe life sales.

(ii) Hides are cleaned by removing hair, epidermis, and flesh and opening pores.

(iii) Hides are tanned. Tanning comes from the Latin tannare meaning oak bark. Tannin is extracted from the bark of various trees. In the early days, tanners maintained their own bark sheds, where bark was stacked, cured and seasoned. Today the tanners buy a tanning liquor.

Vegetable tanning – the most expensive process – takes from several days to six months and produces leather that has excellent abrasion resistance, is tan in color, and has a characteristic leather smell.

Vegetable tanned leather jacket.

Chrome tanning is a one-bath process producing leather that is soft, pliable and grayish in color.

Black horsehide vintage (1950) chromed tanned motorcycle jacket.

Oil tanning process produces chamois.

Chamois leather jacket.

Many other processes are necessary to improve the strength and appearance of leather: bleaching, stuffing (adding hot oils to make it pliable and resistant to cracking), dyeing, staking (flexing and stretching), boarding (developing the grain), buffing and snuffing (skinning off a thin layer or passing over an emery board), and embossing if the grain surface is poor.

Cross-sectional drawing of a strip of leather showing variations in the density of fiber.

In the figure above, it is obvious that the leather varies in the density of fibers from the flesh side to the skin side. Leathers are often split to make them more pliable and more economical. The first layer is called “Top Grain” and it has the typical animal grain, takes the best finish and wears well. Splits must be embossed to have a leather-like grain. Suedes are napped on the flesh side (see diagram below).

Split leather.

Levi leather suede jacket.

In making articles from leather, much skill is needed in cutting garments, gloves, shoe uppers, and hand bags, from relatively small skins. It is said that the French derived the reputation of making the best kid gloves, not because the leather was better, but because they knew how to cut more gloves from one skin.

Elbow length black kid gloves. French kid leather. 1930s Gimbel brothers.

[1] N. Hollen and J. Saddler, Textiles, 3rd Edition, MacMillan Company, London (1968).

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